Abstract

Polymer bulk heterojunction photovoltaic cell was fabricated by inserting a sol–gel derived ZnO thin film as an electron collecting layer between the fluorine-doped SnO2 (FTO) and polymer-fullerene blend active layer. We demonstrated that the performance of device depends on sol concentration and the sol–gel process. Ammonia treatment on the ZnO film improved the efficiency of the device due to the effective removal of acetate group on the film. The short circuit current density was further increased by fine-tuning the thickness of ZnO film. The photovoltaic cell with this structure (FTO/ZnO film/polymer-fullerene blend/Au) produced a power conversion efficiency of 2.01% under simulated AM1.5G illumination of 100 mW/cm2.